The continuous casting of molten metal in a peripheral groove around a rotating casting wheel is well known in the metal foundry art. Typically, such an apparatus consists of a rotatable casting drum or wheel having an annular peripheral groove, the outer open side of which is enclosed along a portion of its arcuate length by an overlying endless flexible band or belt to form an elongate arcuate molding passageway for receiving molten metal. The endless belt is supported by rollers or wheels to move with the wheel and advance the metal through the molding passageway. Suitable cooling means are provided adjacent the passageway to cool and at least partially solidify the molten metal during its passage about the wheel. Molten metal is introduced into the molding passageway through an upper opening of the passageway formed at the point where the moving belt initially contacts the periphery of the wheel and the solidified metal in the form of a rod or bar is removed from the passageway through a lower opening formed at the point where the belt separates from the periphery of the wheel. The molten metal leaving the lower opening of the passageway in the shape of a rod of indefinite length is thereafter subjected to further conventional processing operations such as rolling, milling, stretching and the like.
At the start-up of such a continuous metal casting operation, and before the molten metal is initially poured into the passageway, it is a practice to temporarily block the passageway at a position along its length to prevent the molten metal from running out of the lower opening of the passageway before it has sufficiently solidified by cooling. For this purpose, a metal plug, generally a short length of metal bar, known as a "dummy bar," is physically wedged by force into an intermediate position of the passageway to contain the initially introduced molten metal therein until it has at least partially solidified. When the molten metal is sufficiently solidified, it becomes physically attached to the upper end of the plug or bar. The casting wheel is then set in rotation and the bar is manually pulled from its wedged position by an attached chain or extracting device to remove the bar and leading end of the solidified metal from the lower opening of the passageway. The dummy bar is separated from the end of the cast metal rod and the rod is then directed through the further processing operations.
It can be appreciated that the temporary plugging operation described presents many problems. Difficulty is encountered in physically wedging the dummy bar at the desired intermediate position of the passageway with sufficient force to insure that it will remain in place to support the molten metal until it has sufficiently solidified. Considerable effort is also required to physically dislodge the dummy bar from its wedged position as the casting wheel is set in rotation. The physical wedging of the bar in the molding passageway can also damage the surface of the peripheral groove of the casting wheel.
It is therefore an object of the present invention to provide a continuous metal casting apparatus employing an improved starting plug or dummy bar to initially contain the molten metal in the molding passageway.
It is a more specific object of the present invention to provide a continuous casting apparatus having additional means for positively retaining and readily releasing a starting bar or blocking member from an intermediate position of the casting passageway during initial start-up of the casting operation.
It is another object of the present invention to provide an improved method for continuously casting molten metal into a rod of indefinite length.